[Mesa-dev] [PATCH] softpipe: fix seamless cube filtering
Brian Paul
brianp at vmware.com
Thu Oct 10 23:12:10 CEST 2013
On 10/10/2013 11:37 AM, sroland at vmware.com wrote:
> From: Roland Scheidegger <sroland at vmware.com>
>
> Fix coord wrapping (and face selection too) in case of edges.
> Unfortunately, the coord wrapping is way more complicated than what
> the code did, as it depends on the face and the direction where the
> texel falls off the face (the logic needed to get this right in fact
> seems utterly ridiculous).
> Also fix a bug in (y direction under/overflow) face selection.
> And get rid of complicated cube corner handling. Just like edge case,
> the coord wrapping was wrong and it seems very difficult to fix.
> I'm near certain it can't always work anyway (though ordinary seamless
> filtering on edge has actually a similar problem but not as severe)
> because we don't have per-pixel face, hence could have multiple corner
> texels which would make it very difficult to average the remaining texels
> correctly. Hence simply pick a texel which would only have fallen off one
> edge but not both instead, which is not quite accurate but actually I think
> should be enough to meet OpenGL (but not d3d10) requirements.
> ---
> src/gallium/drivers/softpipe/sp_tex_sample.c | 200 +++++++++++++++++++-------
> 1 file changed, 150 insertions(+), 50 deletions(-)
>
> diff --git a/src/gallium/drivers/softpipe/sp_tex_sample.c b/src/gallium/drivers/softpipe/sp_tex_sample.c
> index 8dcc297..b905790 100644
> --- a/src/gallium/drivers/softpipe/sp_tex_sample.c
> +++ b/src/gallium/drivers/softpipe/sp_tex_sample.c
> @@ -608,6 +608,48 @@ get_texel_2d(const struct sp_sampler_view *sp_sview,
> }
> }
>
> +
> +/*
> + * Here's the complete logic (HOLY CRAP) for finding next face and doing the
> + * corresponding coord wrapping, implemented by get_next_face,
> + * get_next_xcoord, get_next_ycoord.
> + * Read like that (first line):
> + * If face is +x and s coord is below zero, then
> + * new face is +z, new s is max , new t is old t
> + * (max is always cube size - 1).
> + *
> + * +x s- -> +z: s = max, t = t
> + * +x s+ -> -z: s = 0, t = t
> + * +x t- -> +y: s = max, t = max-s
> + * +x t+ -> -y: s = max, t = s
> + *
> + * -x s- -> -z: s = max, t = t
> + * -x s+ -> +z: s = 0, t = t
> + * -x t- -> +y: s = 0, t = s
> + * -x t+ -> -y: s = 0, t = max-s
> + *
> + * +y s- -> -x: s = t, t = 0
> + * +y s+ -> +x: s = max-t, t = 0
> + * +y t- -> -z: s = max-s, t = 0
> + * +y t+ -> +z: s = s, t = 0
> + *
> + * -y s- -> -x: s = max-t, t = max
> + * -y s+ -> +x: s = t, t = max
> + * -y t- -> +z: s = s, t = max
> + * -y t+ -> -z: s = max-s, t = max
> +
> + * +z s- -> -x: s = max, t = t
> + * +z s+ -> +x: s = 0, t = t
> + * +z t- -> +y: s = s, t = max
> + * +z t+ -> -y: s = s, t = 0
> +
> + * -z s- -> +x: s = max, t = t
> + * -z s+ -> -x: s = 0, t = t
> + * -z t- -> +y: s = max-s, t = 0
> + * -z t+ -> -y: s = max-s, t = max
> + */
> +
> +
> /*
> * seamless cubemap neighbour array.
> * this array is used to find the adjacent face in each of 4 directions,
> @@ -617,49 +659,101 @@ static const unsigned face_array[PIPE_TEX_FACE_MAX][4] = {
> /* pos X first then neg X is Z different, Y the same */
> /* PIPE_TEX_FACE_POS_X,*/
> { PIPE_TEX_FACE_POS_Z, PIPE_TEX_FACE_NEG_Z,
> - PIPE_TEX_FACE_NEG_Y, PIPE_TEX_FACE_POS_Y },
> + PIPE_TEX_FACE_POS_Y, PIPE_TEX_FACE_NEG_Y },
> /* PIPE_TEX_FACE_NEG_X */
> { PIPE_TEX_FACE_NEG_Z, PIPE_TEX_FACE_POS_Z,
> - PIPE_TEX_FACE_NEG_Y, PIPE_TEX_FACE_POS_Y },
> + PIPE_TEX_FACE_POS_Y, PIPE_TEX_FACE_NEG_Y },
>
> /* pos Y first then neg Y is X different, X the same */
> /* PIPE_TEX_FACE_POS_Y */
> { PIPE_TEX_FACE_NEG_X, PIPE_TEX_FACE_POS_X,
> - PIPE_TEX_FACE_POS_Z, PIPE_TEX_FACE_NEG_Z },
> + PIPE_TEX_FACE_NEG_Z, PIPE_TEX_FACE_POS_Z },
>
> /* PIPE_TEX_FACE_NEG_Y */
> { PIPE_TEX_FACE_NEG_X, PIPE_TEX_FACE_POS_X,
> - PIPE_TEX_FACE_NEG_Z, PIPE_TEX_FACE_POS_Z },
> + PIPE_TEX_FACE_POS_Z, PIPE_TEX_FACE_NEG_Z },
>
> /* pos Z first then neg Y is X different, X the same */
> /* PIPE_TEX_FACE_POS_Z */
> { PIPE_TEX_FACE_NEG_X, PIPE_TEX_FACE_POS_X,
> - PIPE_TEX_FACE_NEG_Y, PIPE_TEX_FACE_POS_Y },
> + PIPE_TEX_FACE_POS_Y, PIPE_TEX_FACE_NEG_Y },
>
> /* PIPE_TEX_FACE_NEG_Z */
> { PIPE_TEX_FACE_POS_X, PIPE_TEX_FACE_NEG_X,
> - PIPE_TEX_FACE_NEG_Y, PIPE_TEX_FACE_POS_Y }
> + PIPE_TEX_FACE_POS_Y, PIPE_TEX_FACE_NEG_Y }
> };
>
> static INLINE unsigned
> -get_next_face(unsigned face, int x, int y)
> +get_next_face(unsigned face, int idx)
> {
> - int idx = 0;
> + return face_array[face][idx];
> +}
>
> - if (x == 0 && y == 0)
> - return face;
> - if (x == -1)
> - idx = 0;
> - else if (x == 1)
> - idx = 1;
> - else if (y == -1)
> - idx = 2;
> - else if (y == 1)
> - idx = 3;
> +static INLINE unsigned
I think that the return type should be int.
> +get_next_xcoord(unsigned face, unsigned fall_off_index, int max, int xc, int yc)
> +{
> + if ((face == 0 && fall_off_index != 1) ||
> + (face == 1 && fall_off_index == 0) ||
> + (face == 4 && fall_off_index == 0) ||
> + (face == 5 && fall_off_index == 0)){
> + return max;
> + }
> + if ((face == 1 && fall_off_index != 0) ||
> + (face == 0 && fall_off_index == 1) ||
> + (face == 4 && fall_off_index == 1) ||
> + (face == 5 && fall_off_index == 1)) {
> + return 0;
> + }
> + if ((face == 4 && fall_off_index >= 2) ||
> + (face == 2 && fall_off_index == 3) ||
> + (face == 3 && fall_off_index == 2)){
> + return xc;
> + }
> + if ((face == 5 && fall_off_index >= 2) ||
> + (face == 2 && fall_off_index == 2) ||
> + (face == 3 && fall_off_index == 3)){
> + return max - xc;
> + }
> + if ((face == 2 && fall_off_index == 0) ||
> + (face == 3 && fall_off_index == 1)) {
> + return yc;
> + }
> + else {
> + /* (face == 2 && fall_off_index == 1) ||
> + (face == 3 && fall_off_index == 0)) */
> + return max -yc;
space after -
> + }
> +}
>
> - return face_array[face][idx];
> +static INLINE unsigned
return int
> +get_next_ycoord(unsigned face, unsigned fall_off_index, int max, int xc, int yc)
> +{
> + if ((fall_off_index <= 1) && (face <= 1 || face >= 4)) {
> + return yc;
> + }
> + if (face == 2 ||
> + (face == 4 && fall_off_index == 3) ||
> + (face == 5 && fall_off_index == 2)) {
> + return 0;
> + }
> + if (face == 3 ||
> + (face == 4 && fall_off_index == 2) ||
> + (face == 5 && fall_off_index == 3)) {
> + return max;
> + }
> + if ((face == 0 && fall_off_index == 3) ||
> + (face == 1 && fall_off_index == 2)) {
> + return xc;
> + }
> + else {
> + /* (face == 0 && fall_off_index == 2) ||
> + (face == 1 && fall_off_index == 3) */
> + return max - xc;
> + }
> }
>
> +
> +
> static INLINE const float *
> get_texel_cube_seamless(const struct sp_sampler_view *sp_sview,
> union tex_tile_address addr, int x, int y,
> @@ -668,44 +762,47 @@ get_texel_cube_seamless(const struct sp_sampler_view *sp_sview,
> const struct pipe_resource *texture = sp_sview->base.texture;
> unsigned level = addr.bits.level;
> unsigned face = addr.bits.face;
> - int new_x, new_y;
> - int max_x, max_y;
> - int c;
> + int new_x, new_y, max_x;
>
> max_x = (int) u_minify(texture->width0, level);
> - max_y = (int) u_minify(texture->height0, level);
> +
> + assert(texture->width0 == texture->height0);
> new_x = x;
> new_y = y;
>
> - /* the corner case */
> - if ((x < 0 || x >= max_x) &&
> - (y < 0 || y >= max_y)) {
> - const float *c1, *c2, *c3;
> - int fx = x < 0 ? 0 : max_x - 1;
> - int fy = y < 0 ? 0 : max_y - 1;
> - c1 = get_texel_2d_no_border( sp_sview, addr, fx, fy);
> - addr.bits.face = get_next_face(face, (x < 0) ? -1 : 1, 0);
> - c2 = get_texel_2d_no_border( sp_sview, addr, (x < 0) ? max_x - 1 : 0, fy);
> - addr.bits.face = get_next_face(face, 0, (y < 0) ? -1 : 1);
> - c3 = get_texel_2d_no_border( sp_sview, addr, fx, (y < 0) ? max_y - 1 : 0);
> - for (c = 0; c < TGSI_QUAD_SIZE; c++)
> - corner[c] = CLAMP((c1[c] + c2[c] + c3[c]), 0.0F, 1.0F) / 3;
> -
> - return corner;
> - }
> /* change the face */
> if (x < 0) {
> - new_x = max_x - 1;
> - face = get_next_face(face, -1, 0);
> + /*
> + * Cheat with corners. They are difficult and I believe because we don't get
> + * per-pixel faces we can actually have multiple corner texels per pixel,
> + * which screws things up majorly in any case (as the per spec behavior is
> + * to average the 3 remaining texels, which we might not have).
> + * Hence just make sure that the 2nd coord is clamped, will simply pick the
> + * sample which would have fallen off the x coord, but not y coord.
> + * So the filter weight of the samples will be wrong, but at least this
> + * ensures that only valid texels near the corner are used.
> + */
> + if (y < 0 || y >= max_x) {
> + y = CLAMP(y, 0, max_x - 1);
> + }
> + new_x = get_next_xcoord(face, 0, max_x -1, x, y);
> + new_y = get_next_ycoord(face, 0, max_x -1, x, y);
> + face = get_next_face(face, 0);
> } else if (x >= max_x) {
> - new_x = 0;
> - face = get_next_face(face, 1, 0);
> + if (y < 0 || y >= max_x) {
> + y = CLAMP(y, 0, max_x - 1);
> + }
> + new_x = get_next_xcoord(face, 1, max_x -1, x, y);
> + new_y = get_next_ycoord(face, 1, max_x -1, x, y);
> + face = get_next_face(face, 1);
> } else if (y < 0) {
> - new_y = max_y - 1;
> - face = get_next_face(face, 0, -1);
> - } else if (y >= max_y) {
> - new_y = 0;
> - face = get_next_face(face, 0, 1);
> + new_x = get_next_xcoord(face, 2, max_x -1, x, y);
> + new_y = get_next_ycoord(face, 2, max_x -1, x, y);
> + face = get_next_face(face, 2);
> + } else if (y >= max_x) {
> + new_x = get_next_xcoord(face, 3, max_x -1, x, y);
> + new_y = get_next_ycoord(face, 3, max_x -1, x, y);
> + face = get_next_face(face, 3);
> }
>
> addr.bits.face = face;
> @@ -1241,6 +1338,7 @@ img_filter_cube_nearest(struct sp_sampler_view *sp_sview,
> wrap_nearest_clamp_to_edge(s, width, &x);
> wrap_nearest_clamp_to_edge(t, height, &y);
> } else {
> + /* Would probably make sense to ignore mode and just do edge clamp */
> sp_samp->nearest_texcoord_s(s, width, &x);
> sp_samp->nearest_texcoord_t(t, height, &y);
> }
> @@ -1524,17 +1622,19 @@ img_filter_cube_linear(struct sp_sampler_view *sp_sview,
> * For seamless if LINEAR filtering is done within a miplevel,
> * always apply wrap mode CLAMP_TO_BORDER.
> */
> - if (sp_samp->base.seamless_cube_map) {
> + if (1||sp_samp->base.seamless_cube_map) {
> + /* Note this is a bit overkill, actual clamping is not required */
> wrap_linear_clamp_to_border(s, width, &x0, &x1, &xw);
> wrap_linear_clamp_to_border(t, height, &y0, &y1, &yw);
> } else {
> + /* Would probably make sense to ignore mode and just do edge clamp */
> sp_samp->linear_texcoord_s(s, width, &x0, &x1, &xw);
> sp_samp->linear_texcoord_t(t, height, &y0, &y1, &yw);
> }
>
> addrj = face(addr, face_id);
>
> - if (sp_samp->base.seamless_cube_map) {
> + if (1||sp_samp->base.seamless_cube_map) {
> tx0 = get_texel_cube_seamless(sp_sview, addrj, x0, y0, corner0);
> tx1 = get_texel_cube_seamless(sp_sview, addrj, x1, y0, corner1);
> tx2 = get_texel_cube_seamless(sp_sview, addrj, x0, y1, corner2);
>
Maybe add a comment on get_next_xcoord(), etc. But LGTM.
Reviewed-by: Brian Paul <brianp at vmware.com>
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